In the sector of sanitary articles wearable as pants (nappies for small children and newborns, diapers for incontinent persons, etc.), there has continued to assert itself to an increasing extent the general structure represented, by way of example, in FIG. 1, where an article of the type considered herein is represented in the splayed-out condition and with the surface that is in contact with the body of the user facing the observer.
An article 10 of this sort is constituted by a central body or “chassis” 12 that is to be set according to a general concave configuration around the groin area of the user. The body 12 includes an absorbent core 15 sandwiched between a topsheet 13, which may be partially or totally permeable to body liquids, and an impermeable backsheet 14.
To enable the article 10 to be worn like pants, closing it around the waistline of the user, side panels are present, i.e., laminar elements, namely, a rear laminar element 16 and a front laminar element 18, that can be connected in a closed condition around the waistline of the user by means of closing elements 20 set at the distal margins 161 of the side panels 16.
The side panels 16 are particularly complex and sophisticated closing systems. To meet the needs of use in a complete way, the side panel must both perform functions of a structural nature (enabling closing of the sanitary article around the legs and the waist region of the user, ensuring the maximum degree of wearability) and enable transpiration of the skin preventing undesirable phenomena of maceration of the user's skin due to local stagnation of the moisture.
Examples of structures of sanitary articles inspired by said arrangement are illustrated, for example, in the documents Nos. EP-A-0 669 121 or WO-A-95/17871.
To guarantee a good wearability of the sanitary product, the rear panel 16 must have a trapezial shape, with the internal edge 163 shaped so as to form an obtuse angle with the longitudinal axis X1 of the diaper. Conversely, the external edge 162 can be perpendicular to the aforesaid axis X1 or, as in the case illustrated herein, can also present an obtuse angle of the same amplitude, in absolute value, but with a direction contrary to the one formed by the aforesaid internal edge 163.
Examples of methods for producing absorbent products with side panels with the two edges, the outer one 162 and the inner one 163, that do not form an angle of the same amplitude with the axis X1 of the diaper, i.e., with the side panels that have an asymmetrical conformation, are illustrated in the documents No. EP-A-1 941 853 and Italian Patent Application No. CH10A000015.
The methods described in the aforesaid documents present, however, problems; namely: for the method described in Italian Patent Application No. CH10A000015 there is an important limitation linked to the cost of the absorbent product; in fact, the aforesaid method teaches to provide a profiling of the panel by making on the latter a shaped cut, with corresponding removal and discarding of raw material, which for these particular applications is very costly.
As regards the document No. EP-A-1 941 853, which teaches to provide a diaper with side panels with asymmetrical shaping without generation of waste material, the drawback of the solution is to be sought in the complexity of the equipment, which hence reflects in an excessive cost of the production line and in the need to have available skilled staff for managing and running the production plant.
In general, the inventor has noted that, having to cut out shaped elements from a strip or web of raw material, it is possible to select profiles of the elements in question such as to create a situation of geometrical complementarity of the outlines of said elements, i.e., such as to have the two angles formed by the side edges of the panels with the longitudinal axis of the absorbent product of the same amplitude. For example, from FR-A-2 644 694 a solution is known in which, having to provide winged-type sanitary pads for women the starting point is a web that is cut lengthwise according to an approximately sinusoidal cutting path. The two half-strips thus obtained are turned over and connected back to back so as to obtain a weblike material with the desired profiling without giving rise to waste material.
An intrinsic drawback of this type of solution lies, however, in the fact that to the side panels thus formed it is not possible to associate projecting closing elements, unless by applying them to the individual panels after the latter have been cut. The inventor has found that the operation just suggested proves to be of an extreme complexity; consequently, a solution of this type limits considerably the possibility of choice of closing elements to just non-projecting elements applied directly on the side panels.